1. Field of Invention
This invention relates to catheter devices which rely on guidewires to direct the catheter to a desired location within a body. More particularly, this invention relates to guidewire controllers.
2. Previous Art
As described in U.S. Pat. Nos. 5,250,059; 5,084,010 and 4,479,952 which are specifically incorporated herein by reference, there exists a plethora of different catheter designs. Where directional atherectomy catheters are used, it is desirable to employ a guidewire to guide the catheter to the desired position within a body.
Typically, the catheter has a drive unit attached to a torque cable for rotating (or rotationally oscillating) a work element. The torque cable (cable) has a hollow interior. One end of the cable connects to the drive unit and the other end connects to the work element. Work elements include, for example, cutting devices, ablation elements and telemetry devices.
A guidewire slides within the hollow interior of the torque cable in order to guide the catheter into a desired location within the body. The guidewire, for example, can guide an atherectomy catheter to an occluded region in the vasculature of a human body.
The guidewire is manipulated to the desired location by rotating and feeding the guidewire from the drive unit through the torque cable. This feeding may be accomplished by hand, or otherwise.
The drive unit rotates the torque cable. A drive unit is disclosed in U.S. Pat. No. 4,771,774 which is incorporated herein by reference. A torque cable is disclosed in commonly assigned U.S. patent application Ser. No. 08/606,678 filed Feb. 2, 1996, Attorney Docket No. DEVI1434CON, the file wrapper continuation of U.S. patent application Ser. No. 08/165,058 filed Dec. 9, 1993, which is incorporated herein by reference. Rotation of the torque cable causes sympathetic rotation of the guidewire. Sympathetic rotation is the result of frictional forces developed between the rotating interior of the torque cable and the surface of the guidewire.
The torque cable can also be translated along the longitudinal axis of catheter independently of cutter rotation. Torque cable translation causes sympathetic translation of the guidewire, also known as migration. Migration of the guidewire during operation of the work element is undesirable because the guidewire may interfere with operation of the catheter and the work element. What is desired is a way of controlling the axial migration of the guidewire.
The guidewire must be able to rotate as the sympathetic action between the torque cable and guidewire may varyingly dictate. If the guidewire is kept from rotating at the proximal end, the spinning action of the torque cable against the guidewire may cause one end of the guidewire to twist and wind up with respect to the other end. This can cause the guidewire to deform and fail.
What is needed is a device for controlling guidewire migration along the torque cable. The device should allow the guidewire to spin during rotation and longitudinal motion of the torque cable. The device for controlling the guidewire migration should be adapted for use with various guidewire types, torque cables and drive systems.